Magnetic latch



Sept. 15, 1959 P. c. KORODII MAGNETIC LATCH Filed July 31, 1958 INVENTOR PAUL C. KORODI LM JK $11 \N sill United States Patent 2,904,364 MAGNETIC LATCH Paul C. Korodi, Columbus, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 31, 1958, Serial No. 752,324

3 Claims. (Cl. 292-2515 This invention relates to magnetic latches and particularly to magnetic latches of the type used on domestic refrigerators and the like.

The primary object of this invention is the reduction of the cost of a magnetic latch which possesses sufficient holding power to enable it to be used with the heavy doors or closures of insulated cabinets, such as refrigerator cabinets. Simplicity of construction, ease of assembly, and utilization of inexpensive materials are, therefore, attributes of latches employing this invention.

In accordance with this invention, the magnet assem bly for the magnetic latch includes a casing or housing for the permanent magnet material, which casing completely covers the magnetized face of the magnet, providing a protective and decorative cover therefor. The casing also includes a back wall member formed of magnetically permeable material which engages the rear face of the magnet material and is held in place by deformed portions of the casing side walls which are formed integral with the front wall of the casing. The magnet assembly is particularly easy to assemble; the procedure merely including the steps of inserting the magnet material into a preformed casing component providing the front and side walls of the casing, placing the casing back wall over the magnetic material, and thereafter deforming portions of the casing side walls so that they engage the back face of the back wall member and hold the assembly together. No additional fastening means are required to complete the magnet assembly.

It is also contemplated that the casing for the magnetic material also include projecting portions, or extensions, which are utilized in mounting the magnet structure in the cabinet or on the door thereof. In one embodiment of the invention these mounting extensions are formed integrally with the back wall member of the casing, and in another embodiment of the invention the extensions are formed integrally with the front wall portion of the casing. In either event, the arrangement is such as to facilitate mounting the magnet assembly in a resilient and adjustable supporting system.

Other objects, advantages and features of the inven tion will become apparent from the following detailed description of the invention in which reference is made to the accompanying drawings wherein:

Fig. 1 is a fragmentary side view of a refrigerator cabinet having portions thereof broken away to show the magnetic latch incorporating this invention;

Fig. 2 is a vertical sectional view through the magnet assembly of the latch shown in Fig. 1;

Fig. 3 is a perspective view of the upper portion of the magnet assembly shown in Fig. 2;

Fig. 4 is a vertical sectional view through a modified magnet assembly; and

Fig. 5 is a perspective view of the upper portion of the modified magnet assembly.

Referring first to the embodiment of the invention illustrated in Figs. 1 to 3, the latch comprises a magnet "ice assembly 11 and an armature 12 which is attraotable to the magnet assembly. These components are adapted to be mounted, respectively, on a door 13 and a cabinet 14 forming a part of a domestic refrigerator or the like. If desired, the positions of the magnet assembly 11 and the armature 12 can be reversed, although the magnet assembly preferably is carried by the door.

The magnet assembly 11 includes a two piece casing or housing assembled from an elongated cup-like receptacle 16 and an elongated back wall member 18. Disposed in end-to-end relationship within the casing are a pair of elongated permanent magnets 17. The receptacle 16 is formed of non-magnetic material, such as thin aluminum sheeting, and has a front wall portion 19 which covers the face of the magnets 17. The receptacle 16 also includes side wall portions 21 formed integral with the front wall portion 19. Rear edge portions 22 of the side walls 21 are bent or deformed around the rear face of the casing rear wall member 18 and serve as an inexpensive means for holding the several components of the magnet assembly 11 together.

In accordance with this invention, each of the permanent magnets 17 is magnetized to possess at least two, and preferably three, magnetic poles on the face thereof which is in engagement with the front wall 19 of the receptacle 16. An inexpensive, ceramic-like, permanent magnet material, such as barium ferrite, is preferably employed in the construction of the magnets 17. This magnetic material has low permeability, of the order of 1.5, and magnets made therefrom can possess closely spaced magnetic poles on a single face thereof. A preferred pole disposition on the front face of the magnets is indicated in Fig. 2 by the letters N and S. With such a magnetic pole arrangement, greater holding power can be obtained if the back face of each magnet is arranged adjacent a plate or strip of magnetically permeable material, such as soft iron or steel. In the interest of improving the magnetic circuit of the magnet assembly 11, the back wall member 18 of the magnet casing is preferably formed of steel, or other relatively permeable metal.

The two magnets 17 are preferably magnetized so that the poles near the adjoining ends of the two magnets are magnetically alike. (See Fig. 2.) Locating like poles of the individual magnets adjacent one another insures that there will be no shorting of the magnetic field from one magnet to the other, so that maximum reach-out, i.e. maximum dispersion of the magnetic field from the front of the magnet assembly 11, can be obtained.

The back wall member 18 of the magnet casing 15 has end extensions 23 that are utilized in mounting the magnet assembly on the door 13, and for this purpose the extensions have holes 24 therein. The preferred mounting arrangement is illustrated in Fig. 1 and it will be noted that the magnet assembly 11 is carried by a pair of bolts 26 which pass through the aforementioned holes in the mounting extensions 23 of the casing member 18. These bolts are screwed into self-supporting nuts 27 carried by brackets 28 suitably mounted in the interior of the door 13. Concentn'cally disposed about the bolts 26, between the casing extensions 23 and the nuts 27, are springs 29 which resiliently bias the extension 23 against the heads of the bolts. These springs 29 permit movement of the magnet assembly along the bolts 26 and relative the door 13 for the purpose of absorbing impact forces resulting from the magnet assembly 11 engaging the fixed armature 12 as the door is closed.

I Only a narrow elongated slot need be provided in the inner face of the door 13 for receiving the magnet assembly 11 and most of this opening is filled by the smooth front wall 19 of the magnet casing. The magnet assembly 15 thus presents a neat and unobtrusive appearance in conjunction with the inner face of the door 13 when the door is open. The appearance of the latch can be further enhanced by providing decorative covers 31 Second embodiment The embodiment of the invention illustrated in Figs. .4 and utilizes the same basic principles of simplicity of construction as the previously disclosed embodiment. In the modified magnet assembly, designated generally by the reference numeral 34, a molded plastic receptacle 35 is utilized to form the front and side wall portions of a magnet casing 36. The receptacle 35 is preferably made from a thermoplastic material, such as polystyrene plastic. Like the preceding embodiment, a back wall member 37 for the casing 36 is held in place by deformed portions 38 of the side walls of receptacle 35. These portions 38 of the receptacle project through openings provided therefor in the back wall member 37 (see Fig. 5) and are deformed by the application of heat and pressure to overlap adjoining areas of the rear face of the wall member 37. It will be noted that this securing procedure for the magnet casing 36 can be quickly and inexpensively performed.

Disposed within the casing 36 is a permanent magnet 39' formed of barium ferrite or other ceramic-like magnetic material. The magnet 39 has two unlike magnetic poles (indicated by N and S in Fig. 4) on the face thereof which abuts the front wall portion of receptacle 35. Also disposed within the casing 36 is a relatively heavy flux plate 41 which is in contact with the back face of the magnet 39. This plate 41 is made from metal having high magnetic permeability and is of sufiicient crosssectional area to carry all of the magnetic flux of the magnet 39' without becoming saturated. As mentioned previously, the ceramic-like magnetic materials have very low permeability, and providing a low reluctance flux path at the back of themagnet by means of the flux plate 41, instead of requiring the fiux to pass longitudinally through the body of the magnet 39, enables the attractive force of'the magnet to be increased. This principle is discussed in greater detail and the magnet structure is claimed in the copending application of Laurance D. Burgess, Serial No. 613,851, filed October4, 1956' andassigned to the same assignee as this application. The casing rear wall member'37 is also preferably made from metal having high magnetic permeability to supplement the flux path provided by the flux plate 41, although member 37 can be made of lower cost'material, such as plastic sheet.

Both the magnet 39 and the flux plate 41 are retained within the receptacle 35 by virtue of the engagement of the deformed portions '38 of the receptacle with the back wall member 37, this being the sole means for securing the components of the magnet assembly together.

In conjunction with the molded plastic receptacle portion of the modified magnet assembly 11, it is economical to mold end projections 42 integrally with the receptacle. These projections 4-2 have holes therein which enable the modified magnet assembly to be mounted on the door 13in the manner illustrated in Fig. 1 and described above.

From the foregoing it will be apparent this invention enables a permanent magnet latch to be constructed both easily and inexpensively, thereby permitting more widespread use of such latches than was'heretofore considered to be economical.

While the invention has been described in connection with but two embodiments thereof, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.

What is claimed is:

1. A magnetic latch for holding a door member in closed position relative a cabinet member and comprising an armature element mounted on one of said members, a casing adapted to be carriedby the other of'said members, said casing having a front wall adapted to engage said armature and side walls integral with said front wall, all of said walls-being formed of'a non-magnetic material, a permanent magnet magnetized to possess at least two unlike magnetic poles on one face thereof and disposed within said casing with said one face in engagement with the front wall of the casing, said casing including arear wall member, said casing sidewalls having rear-edge portions thereof formed inoverlapping engagement with said rear wall member and constituting the sole means for retaining said rear wall member in placeand said magnetinthe casing, said-casing having projecting portionsextendingfrom the ends thereof, and means for attachingth'e said projecting portions of the' casing to said other member.

2. A magnetic latch for holding a door member in closed position-relative a cabinet member and comprise ing an armature elementmounted on one of said members; a casing-adapted .to be carried by the other of said members, said. casing having a front wall adapted to engagesaid armature and side walls integral with said front Wall, all of saidwalls being formed of a non-magnetic material, a permanent magnet magnetized'to possess. at least two unlike magnetic poles on one face thereof and disposed within said casing with said one face in engagement with the front wall of the casing, said casing including arear wall member formed of magnetically permeable material, said casing side walls having rear edge p'ortionsthereof formed in overlapping engagement with said rear wall member and constituting the sole means for retaining said rear wall member-in place and said magnet in the casing, said rear wall member having end portions extending beyond the front and side walls of said casing, and means for attaching said portions of the rear wall member to said other member.

3. A magnetic latch for holding a door member in closed position relative a cabinet member andcomprising' an armature element mounted in one of said members, .a casing adapted to be carried by the other of-said members, said casing, comprising a receptacle having a front wall and spaced side walls and a rear wall member, the side walls .of said receptacle having rear edge por tions thereof deformed by the application of heat and pressure into overlapping engagement with said rear wall member, a permanent magnet magnetized to possess at least two unlike poles -on one face thereof, said magnet being disposed within said casing with said one face in engagement with the front wall of said receptacle and the opposite face thereof in engagement with said rear wall member, said overlapping portions of the receptacle side walls constituting the sole means for retaining said rear wall member onsaid receptacle and said magnet in said casing, saidv casing having projecting portionsextending from the ends thereof, and means for attaching said projecting portions of the casing to said other member.

ReferencesCited in the file of this patent UNITED STATES PATENTS 2,867,467 Foley Jan. 6, 1959 

